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The invention relates generally to rollers. In particular, the invention relates to rollers used in conjunction with road construction apparatus.
Paved roads or pathways predate the dawn of written history. Early civilizations sometimes used loose material such as gravel or small stones as paving materials. Such materials represented an enormous advancement from worn earthen trails that were alternatively muddy quagmires during rainy seasons and hard ribbons of choking dust otherwise.
Today, materials such as gravel are still used as paving material, either alone or as a base material for other surfaces such as asphalt and concrete. The quality and durability of the finished paving requires that the base layers be compacted to provide a relatively uniform base surface. This is typically accomplished in road construction by first grading the material, then using compaction devices known as rollers or packers. Rollers come in a variety of configurations, ranging from manually propelled walk-behind devices to sophisticated motorized vehicles
It has also been proposed to use road construction vehicles such as graders or bulldozers to tow roller assemblies. One example of such an arrangement is described in U.S. Pat. No. 3,291,013 to Stolp. This patent is directed to a wheeled trailer type compactor in which front and rear banks of compactor wheels are independently mounted in pairs. The pairs of wheels are journaled in spring mounted shackles to permit the compactor wheels to follow ground contours.
U.S. Pat. No. 3,993,413 to Cox describes a road packer in which a plurality of pneumatic tires are mounted on shafts. A double acting cylinder is provided to lift the packer for transport, or push down on the packer during operation.
U.S. Pat. No. 4,909,663 to Freeman sets forth a road making apparatus in which a single row of roller tires is secured to a draft vehicle.
While each of these arrangements provides the advantages of dual usage for conventional construction vehicles, they have certain drawbacks in the efficacy of their rolling operation For example, known towed rollers rely upon force, applied through weights (as in Freeman) or hydraulics (as in Stolp and Cox), to achieve a uniform surface. The problems presented by irregularities in the roadbed are either not addressed, or approached with relatively complicated and largely ineffective spring suspensions as in Stolp.
It can be seen from the foregoing that the need exists for a simple, reliable arrangement for rollers that will yield a uniform paving surface despite irregularities in the roadbed.
These and other objects are achieved by providing a roller assembly including a frame member, a plurality of front roller members, and plurality of rear roller members corresponding in number to the plurality of front roller members. A plurality of walking beams are pivotably connected to the frame member. Each of the walking beams connects one of the front roller members with a respective one of the rear roller members.
The front roller members and the rear roller members have respective radial axes. The front and rear roller members are mounted on the walking beams such that the radial axes of the front roller members are offset from the radial axes of the rear roller members. The frame member can include a generally rectangular outer frame, which can be fabricated from tubular steel.
An attachment mechanism can be secured to the frame member to facilitate attachment of the roller assembly to an operating tow vehicle. A hitch mechanism can be secured to the frame member to facilitate attachment of the roller assembly to a second vehicle. The attachment mechanism and the hitch mechanism can be secured on opposite sides of the frame member.
The front roller members and the rear roller members can be provided as wheel and tire assemblies mounted to the walking beams by means of lubricated bushings.
At least one reinforcing beam can be secured to the frame member. In an embodiment, a pair of parallel reinforcing beams are secured at a central portion of the frame member. At least one of the roller members can be mounted between the reinforcing beams.
The roller members can be secured to axles on the walking beams by means of respective pairs of bolt-on clamp members, thus allowing removal of the individual roller members without disassembly of any other roller assembly structure.
The features of the invention believed to be patentable are set forth with particularity in the appended claims. The invention itself, however, both as to organization and method of operation, together with further objects and advantages thereof, may be best understood by reference to the following description taken in conjunction with the accompanying drawings.